Program distributing system



NOV. 20, 1934- DEAK|N ET AL 1,981,689

PROGRAM DI STRIBUTING SYSTEM Filed 'Aug. 16, 1935 2 Sheets-Sheet 1 G. DEA K IN L.J..JSCHRE/BER INVENTORS: g g gfgke (.AJPULLES C.A.W/LLM$E av v A TTORNE Y I a program selector is provided at the central exchange'and actuatedfrom-the subscribers in- Patented Nov. 20, 1934 PROGRAM DISTRIBUTING SYSTEM Gerald Deakin, Louis J. J. Schreiber,.Stanislas. Van Mierlo, Frank de FI-emery, Cornelis A. J; 4, 'Pulles, and Carolus A. Willemse, Paris, France, assignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of New'York I p Application August 16, 1933, Serial No. 685,380 In- France October. 29, 1932 11 Claims.

The present invention relates to improvements in teleprogram systemathat is to say, in sys-- tems permitting the transmission of one or several programs by means of audio-frequency currents on a network, for instance, on a telephone network, in order to give to subscribers, provided with the necessary equipment, the facility of receiving one or more of the "programs transmitted! The present invention has for an object to adapt economically an existing telephon'e'installation for the transmission to certain subscribers of teleprograms, and to do so with a minimum of changes or additions. of the equipment pro-' Another object'of the invention resides 'in the provision of means topermit the addition of a teleprogram system to an existing telephone system Without affecting its working.-

According to one feature-of the invention, the

interference which might be produced between" the ringing current on the telephone line and the teleprogram receiving arrangement is reduced to an acceptable level by means of a rectifying arrangement (for instance, a copper oxide rectifier) adapted to rectify the ringing current, either partly or' totally, and to produce a correspondingvoltage drop in a resistance, which drop is used to bias the amplifier'sufficiently negatively so that the latter opposes the reproduction of the ringing current in the loudspeaker.

According to another featureof the invention,

stallation in order to permit thelatter to connect his line to any one of the'feeders corresponding to the different programs to be transmitted, the

arrangement being such that the connection of the subscriber's line with a' selected feeder is preceded by the connection of the subscribers line with a warning device indicating the nature of, or anyother useful information-regarding the program, to which switched.

Other equally-important features of the inven-' tion will appear more clearly-from a reading of the subscribers' line will bethe following description basedon the accompanying drawings, in which? Fig l represents the arrangement of a sub-' scribers' station provided with teleprogram service and with a broadcast receiver as well as with a phonograph pick -up.

Fig; 2 represents a modification'in the coupling box for the station of a subscriber to a teleprogram. I

Fig. 3 represents schematically an automatic program announcingdevice.

Fig. 1 representsyby way of example, the installation to be provided at the subscriber's station for the teleprogram service. In this figure, the subscriber's station l is a'standard station and'comp'ri'ses a microphone- 2, a ringer 3, a receiver 4, a s'witchhook 5, an induction coil 6' and a calling dial 7. The telephone line 19 is asso-- ciated with the subscribers-station- '1 by means of a coupling box 8 comprising a suitable switching device permitting the operative association of the telephone line 19, either with the subscriber's station 1 bymeans of a branching line 19', or with the teleprogramreceiving equipment shown in the upper part of Fig. 1'. This equipment may be constituted by a deviceadapted to amplify the teleprogram signals in order to permit their reproductionin' a loudspeaker 9. r

In the case of Fig. 1, there is used, as an emplifier, a portion of a radio receiving'set 10 which may also be used for operating a phonograph pick-up 11; a volume control device 12, independent or not of the amplifier, may be provided in the leads associating the coupling device 8 with the amplifier 10. 'Associated with the volume control device for the teleprogram signals, there is provided a push button 13"which may be actuated by the subscriber, thus permitting the sending of signals to the central exchange for choosing the desired program. i

The working of the installation is as follows:

. Establishment of a teleprogram. connection vIt is assumed that the apparatus is in normal condition and that'the subscriber wishes'to be connected with a certain program. For this purpose, the subscriber will first close the switch (not shown on Fig. 1)' feeding the amplifier 10, thenhe will manually actuate the mechanically lock-- .ing clutch relay 14 provided in the coupling device 8, by moving key 20 to the left. In this position the arm 21 is moved upward and permits the closure of contacts a and b and the opening of contact 0, thus establishing the following circuit: ground at the central exchange, battery, rotary electromagnet PS of the program finder, contact a of the cut-off relay COR, telephone line 12, contact a of 14, terminal D of the volume control device 12.

If the subscriber actuates his selecting pushbutton 13, a ground is placed on terminal D by the following circuit: ground from amplifier 10, terminal P2, closed contacts b and c of push-button 13 and terminal D. This ground completes the circuit for the. rotary electromagnet PS which causes the program-selection switch, placed at the central exchange, to advance one step. It will be noted that the selector, instead of advancing one step when energized, could be adapted to advance one step only when deenergized. The subscriber can thus place the switch for program-selection in the desired position by actuating his push-button 13 a suitable number of times.

When the program-selection switch PS reaches the connections corresponding to the desired program, it stops and establishes the following cir cuit: power amplifier AMP of the central exchange for the set program to be distributed on the subscribers"lines, wipers Si and S2 of switch PS, series condensers C1 and C2, contacts a and b of re ay COR, telephone line 19, terminals L1 and L2 of the coupling box 8, closed contacts a and b of clutch relay l4, terminals C and D of coupling box 8, terminals C and D of volume control de vice 12, resistance 18 and condenser 20, adjustable attenuator 17, terminals P1 and P2 and amplifier 10. The currents received from amplifier AM? of the central exchange, are amplified locally and reproduced through the loudspeaker 9. The attenuator 17 is associated with a resistance 18 in series in wire Z1 of the telephone line, in order to avoid harmful unbalance in the line. Condenser 20 is provided in order to avoid flow from the central exchange battery through attenuator 17.

If the subscriber desires to interrupt the program reception, he simply has to out 01f the current feed of amplifier 10.

The teleprogram system of Fig. 1 does not affect the normal operation of telephone station 1, that is to say, the subscriber can always receive incoming calls and can himself efiect calls at any moment during a program reception.

The working of the telephone installation is as follows:

Case of an incoming call Supposing that the subscribers program reception is operating. and that calling current is sent by the central exchange on the telephone line, after the usual working of the cut-off relay COR normally equipped at the central exchange, the clutch-relay 14 is energized under the influence of such current, and releases its arm 21, thus opening its contacts a and b and closing its contact c. The clutch-relay 14 is energized over the following circuit: calling current on the telephone line l1, terminal Ll, of 8, ringer 3, terminal Lz, winding of clutch-relay 14, terminal F of 8, terminal F of 12, contact a of push-button 13, terminal G of the device 12, terminal G of the coupling box 8, terminal L2 of the said box, line Z2; lines Z1 and Z2 lead to the switch-equipment CO at the central exchange. It will be noticcd that by the operation of COR the connection is cut off between the telephone line 19 and power amplifier AMP.

When the armature of clutch-relay 14 releases, the connection is then broken between the teleprograrn apparatus and the telephone line, and the subscriber's station 1 is directly connected through contact 0 of relay 14 withthe terminal L2 of 8. In this manner, the secrecy of the telephone communication is maintained.

It will be noted that the mechanically locking relay 14 takes only a very short time to release its armature and to open contacts a and b, however, during this short interval of time a small part of the ringing current can reach amplifier 10 and be reproduced by the loudspeaker 9, this effect is often undesirable and, to remedy this, a part of the ringing current can be diverted into a rectifying device (for instance, into a rectifier or a combination of dry rectifiers such as copper oxide or selenium rectifiers associated with a resistance), the drop in voltage produced in such resistance being used to block one or several stages of amplifier 10. This device may include a condenser 22 in series and a rectifier 15 in parallel with a resistance 16, associated with the grid circuit of one or several stages of amplifier 10.

It will be seen therefore that the rectified ringing current will permit the blocking of stages of the amplifier in order to avoid any spurious distortion on account of ringing current in the loudspeaker 9. Spurious noise in the loudspeaker, due to ringing current, can also be eliminated by arranging that two practically even parts of calling current reach the loudspeaker 9, sensibly in phase opposition.

Outgoing call Assuming that the installation is in the teleprogram reception position and that the subscriber wishes to make a telephone call, he lifts his receiver, thus closing contacts of switch hook 5. The subscribers loop current will be closed over the following circuit: ground, battery, winding of the rotaryelectromagnet PS, contact a of relay COR, telephone line 12, terminal L2 of 8, terminal G of 8, terminal G of 12, contact a of button 13, terminal F of 12, terminal F of 8, Winding of relay 14, terminal L'z of 8, contact of the dial 7, microphone 2, contact of switchhook 5, winding of coil 6, terminal L1 of 8, telephone line Z1, contact b of relay COR, winding of relay Lr and ground from the central exchange. The rotating electromagnet PS does not operate in this circuit, as it is now in series with line relay Lr. The mechanically locking relay 14 is energized, opens its contacts a and b, and closes its contact 0 and short circuits its own winding by the latter contact over the following circuit: contact c, winding of relay 14, terminal F of 8, terminal F of 12, contact a of button 13, terminal G of 12, terminal G of 8, contact .0. .By the breaking of contacts a and b, the program reception device is disconnected from the telephone line 19, the subscriber can then make his call in the usual manner, either automatically by his calling dial 7, or by asking a telephone operator at the central exchange.

If, after having used his telephone set, the subscriber desires to connect again with the teleprograrn circuit to which he was listening previous to his call, he simply has to operate manually the mechanically locking relay 14.

Means may be provided to automatically con .ouslyduring the transmission of teleprograms.

nect either thesubscribers Station or the program reception. equipment with the telephone line. Such means is disclosed in Fig. 2. When the automatic coupling box is employed it is substituted for the coupling box 8 of Fig. 1, the connections to the contacts a of push-button 13 of volume control device .12' being omitted. Relays R1 and R2 of the coupling box of Fig. 2 are mechanically coupled, relay R1 being shown in the position of rest.

When'there is no telephone communication in progress relay R1 energizes over the following circuit; battery, program switch selector PS, conductor. .12 of the telephone line, winding of relay R1, back contact d of relay Ra conductor lr of the telephone lineIto ground through the winding of line relay Li. Condenser C bridged around the back contact d of relay R1 enables relay R1 to operate completely although contact d is open during the energization of relay R1. When relay R1 is completely energized its arma; ture's are mechanically locked by relay R2 and terminals L1 and L: are now connected to terminals C and D and thence to terminals C and D of the volume control device 12. The subscriber at substation 1 may operate push-button 13 to select any desired teleprogram as discussed in connection with Fig. 1.' l I Should a call be incoming over the telephone line 19 and relay COR be operated the'operating circuit of relay'Ri will be opened but relay R1 being mechanically locked will not release. Ringing current from the central ofllce will be applied over line conductor 12. winding of relay R2 through the substation ringer 3 and line con ductor 11. When the subscriber lifts his receiver,

until the end of the conversation.

Should the calling subscriber at substation 1 initiate a call while relay R1 is operated, relay R2 will operate in a circuit from battery through the program selector magnet PS, line conductor 12, winding of relay R2, the substation loop, line conductor 11 to ground through line relay Lr. Relay R2 operates, unlocking relay R1 which releases since its high resistance winding is now shunted by the induction coil and microphone of station 1. With relay R1 released because the subscriber has either answered an incoming call or has initiated an outgoing call, the station 1 is connected directly to the telephone line 19 and the teleprogram apparatus is disconnected.

Fig. 3 represents the arrangement provided at the central exchange for indicating automatically to the subscriber the nature of the program to which he will be connected after he has actuated his push-button 13 a certain number of times.

The installation of Fig. 3 comprises'bus bars Program 1, Program 2, Program 3, Program 4,

etc., to which are applied currents correspond: ing to the various programs provided 1, 2, 3, 4, etc. A corresponding series of bus bars, fed by currents corresponding to the information to be given to the teleprogram subscribers is provided; these bus bars are shown in ANN1, ANN-2, ANNa, ANN4, etc., on Fig. 3. The announcement of programs can be furnished by means of phonographs, telegraphones, or any other suitable device, actuated at the proper time, or continu- It should also be noted that instead of announcing the program bymeans of sound recording and reproducing devices, use may be made of particular tone or code signals corresponding to eachone of the programs, thus permitting a simple and economical installation for announcing the programs. The working of the program announcing device, shown in Figs 3, is as follows:

As scenes the subscriber causes the opening and the closing of the circuit, by actuating his push-button 13, shown on Fig. 1, the. rotary electromagnetof the program selector PS energizes and causes the latter to advance one step. This operation is repeated until the selector reaches the desiredposition, for instance, that corresponding to Program 2; As soon as PS attracts its; armature, its contact a closes, .thus causing the starting of a finder in the combined alarm and announcing circuit CAN. When this finder has reached the wanted subscriber's line, it closes the circuit for relays ANRI and ANRz, which operate; the relay ANRzcloses its contact a, thus maintaining the said finder on the said 130 subscriber's line, during a lapse of time determined by thecircuit CAN. Relays ANRi and ANR: effect the transfer of the subscribers line from the program bus bars Program to the announcing bus bars ANN. whose selector has been placed in position. 2 therefore receives the, announcement corresponding tothe chosen Program 2. .After a lapse of time determined by the circuit CAN, relays ANRI and ANR: release, and the subscriber's line is automatically retransferred from the bus bars ANN to the 'program bus bars Program.- From this moment the subscriber receives the selected program.

It is clear that the preceding embodiments are given simply by wayof example, and are not limited, as various important modifications can be realized without departing from the limits of the presentinvention'.

What is claimed is: 1

1. In a system for distributing program service over telephone wires, a telephone line, an amplifier and a loud-speaking receiver for receiving program service over said line, and means to minimize the effect of ringing current applied to said line on said loudspeaker comprising a rectifier in a branch of said line, and means to apply said rectified current to said amplifier to block said amplifier.

2. In a system for distributing program servo ice over telephone wires, a telephone line, an amplifier and a loud-speaking receiver for receiving program service over said line, and means to minimize the effect of ringing current applied to said line on said loudspeaker comprising a branch of said line circuit, a rectifier element in said branch circuit arranged to provide a negative potential, and means to apply said negative potential to said amplifier to block said amplifier.

3. In a system for distributing program service over telephone wires, a telephone line, an amplifier and a loudspeaking receiver for receiving program service over said line, and means to minimize the effect of ringing current applied 45 to said line on said loudspeaker comprising a branch of aid line circuit, a rectifier element in parallel with a resistance connected across said branch circuit arranged to provide a negative potential, and means to apply said negative po- 150 The subscriber 1:5

tential to said amplifier to block said amplifier.

4. In a system for distributing program service over telephone wires, a telephone line, a multi-stage amplifier and a loudspeaking receiver for receiving program service over said line, and means to minimize the effect of ringing current applied to said line on said loudspeaker comprising a rectifier in a branch of said line, and means to apply said rectified current to one or more stages of said amplifier to block said amplifier.

5. In a system for distributing program service over telephone wires, a telephone line, a multistage amplifier and a loudspeaking receiver for receiving program service over said line, and means'to minimize the effect of ringing current applied to said line on said loudspeaker comprising a branch of said line' circuit, a rectifier element in parallel with a resistance connected across said branch circuit arranged to provide a negative potential, and means to apply said negative potential to one or more stages of said amplifier.

6. In a system for distributing program service over telephone wires, ajtelephone line, an amplifier and a loudspeaking'receiver for receiving program service over said line, means responsive to ringing current applied to said line to disconnect said loudspeaker from said line, and means to minimize the effect of the initial application of said ringing current to said line on said loudspeaker comprising a rectifier in a branch of said line, and means to apply said scrlber's line, means for selecting a particular program service, separate announcing means for each program service, and means for automatically connecting said line with the announcin means corresponding to a selected program service for a predetermined time.

9. In a program distributing system, a plurality of program carrying circuits, a plurality of announcement carrying circuits corresponding to said program circuits, means for selecting a particular program carrying circuit and means for automatically substituting the corresponding announcement carrying circuit for the selected program circuit for a predetermined interval.

10. In a program distributing system, a plurality of program carrying circuits, a plurality of announcement carrying circuits corresponding with said program circuits, a subscribers line, means controlled over said line for selecting a particular program carrying circuit, and means for automatically connecting said line with the corresponding announcement circuit before connecting said line with said program circuit.

11. In a program distributing system, a plurality of program carrying circuits, a plurality of announcement carrying circuits corresponding with said program carrying circuits, a subscriber's line, a program selecting means, an announcement connecting means individual to each line, means to operate said program selecting means over said line, means responsive to'the operation of said program selecting means to energize said announcement connecting means, said program selecting means and said announcement connecting means being jointly eifective to connect said line to the announcement circuit corresponding to the selected program circuit for a predeter 

